Ape Caves, Mt St Helens Lava Tubes

Activity Notes

The full experience at Ape Cave includes the easy exploration of a spacious lava tube (Lower Cave), followed by more difficult travel through a smaller, longer, and more rugged lava tube (Upper Cave) to an exit. Then, we'll enjoy an easy return hike winding through shady forest and crusty lava formations. While most of the Lower Cave is an easy walk, the Upper Cave involves a great deal of scrambling over jagged lava blocks. Please consider your comfort level in rough terrain before applying.

Ape Cave is one of the longest lava tubes in North America and also one of the most accessible long lava tubes although it was only discovered in 1946. The lava tube formed about 2,000 years ago in an unusual lava flow down Mount Saint Helens’ south flank. About 450 years ago, a lahar flowed through the tube and plugged Ape Cave at its lower end.